Flamingo issues with Windows 10

I recently upgraded to Windows 10. I could reinstall my Rhinos 5 without any problem. But the installation of my Flamingo NxT appeared not possible on Windows 10. I upgraded (for free) the Flamingo software. The installation of this software caused no problems. However, regrettably, I cannot use this software because in keeps on asking for a FL05 key that I do not have. I have a FL03 key.

Please help

The update from Flamingo 3 to Flamingo 5 was free.
You can get your FL50 key here:

Thank you John, that is extremely helpful. Surprisingly, I wasn’t able to get this information from support@Mcneel. I’m not out of the woods yet, because for some reason the FL50 key I received through your link appeared different during the validation process. No idea how I can correct it. So I need support@Mcneel again.

This support group is a true lifeline. May I bother you with an additional question? The background of my perspective window suddenly turned black. No idea what caused it. I would like to turn it back to the ‘normal’ background. Can you please tell me how to do that?

thanks a lot. Edo